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Soft shell Clams
What are they?
Like oysters and mussels, soft shell clams are bivalves. Bi means “two,” and valve
refers to its shells. So a bivalve is an animal that has two shells, both about the same
size, that are joined by a hinge. Inside its shells, soft shell clams have soft bodies.
What do they look like?
You can crush the shells (or valves) of soft shell clams without much effort. They are
thin and very brittle. These shells are dirty white, egg-shaped, and between three
and six inches long.
Where can you find them?
Soft shell clams like to bury themselves in the soft silt and sand at the bottom of intertidal flats. Some of them burrow as deep as a foot
or more under the bottom of the flats.
How do they behave?
When they are small, soft shell clams can crawl about and dig. However, by the time they become adults, they can only move up and
down, using their foot. If they are taken from their homes, they cannot bury themselves again.
These clams are filter feeders. That means that they eat the things they filter out of the water. Soft shell clams have two long tubes,
called siphons, which lie side by side in their long “necks.” With one siphon, they draw in water. The water is filled with tiny bits of
organic materials, phytoplankton, and zooplankton. The tiny food bits are drawn into the clam’s mouth and digested. Afterwards, the
clam squirts out whatever is left over through the other siphon.
The water clams draw in also contains dissolved oxygen, which the clam takes in through its gills.
Clam can extend their siphons very far. In that way, they can bury themselves deep in the silt or sand and still be able to draw in water.
These clams cannot draw their entire necks into their shells because it won’t fit.
What do they eat?
Soft shell clams filter their food from the water. They eat very tiny bits of phytoplankton, small zooplankton, and bacteria.
What eats them?
Many scientists say that the blue crab is the major predator of soft shell clams. However, many other Bay animals eat soft shell clams,
at every stage of their life. This is a list of some of them:
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Very young fish, jellyfish, and comb jellies
Oyster drills, crabs, starfish, horseshoe crabs, whelks, and moon snails
adult and juvenile bottom-dwelling fish, such as spot and winter flounder
Flatworms
Cownose rays
Herring gulls
American eels
Waterfowl such as black ducks and tundra swans
Raccoons
Creature Feature
Soft shell clams can actually live in areas where there is no dissolved oxygen, but only for a short time. Their shells neutralize the lactic
acid that builds up when they have to continue to breathe and eat without oxygen.
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